Ventilating Duration After Painting (Guide for All Paint Types)

Professionals strongly recommend ventilation during and after you have painted a room or something in a room. However, specific durations are rarely mentioned.

For specific durations, the type of paint must be considered. Careful planning, various equipment, and utilizing your current HVAC system can ensure your health and safety during and after a room has been painted.

Why You Need to Ventilate After Painting

Although foul smells can be quite annoying, they often indicate danger, such as toxic gas, rotten food, or something burning. 

Paint fumes may not smell awful, but their scent is strong and can be considered a warning to us that volatile organic compounds (VOCs) are being released during the drying process.

These VOCs are released through degassing. This is the process whereby gases escape from a substance during the drying or curing process. Furniture treated or coated with certain chemicals and paints will continue to degas or off-gas, even when they are dry.

The danger in VOCs stems from the fact that many of them are considered to be carcinogens or cancer-causing chemicals. Carcinogenic VOCs include benzene, methylene chloride, and more. 

Brief exposure to these carcinogens will not cause cancer, but extended exposure over the years can.

In addition, repeated exposure to all VOCs related to painting, not just the carcinogenic ones, has been linked with the development of asthma and allergies.

While painting your house might be considered low-risk in terms of developing chronic conditions related to VOC exposure, there are enough adverse health effects linked to short-term exposure to warrant proper care when painting.

Short-term effects of VOCs include dizziness and bad headaches. The fumes can also be especially dangerous for children, the elderly, and those with compromised immune systems.

Through passive ventilation (just letting the fumes linger and eventually dissipate) most paints can take 14-24 weeks to completely off-gas. So, long after the paint is dry, it can still release harmful chemicals into the air.

As a result, painting your house can end up presenting conditions for longer exposure.  

To avoid dangerous levels of VOCs, active ventilation should be used to remove the dangerous substances quickly and efficiently.

Post-Painting Ventilation Duration

Unfortunately, there is not an all-encompassing recommended time for all kinds of paints. To find how long you should ventilate after painting, the type of paint must be considered. 

Latex and Acrylic (Water-Based) Paints

Latex and acrylic paints are both water-based paints.

Acrylic paint is known as a universal paint because it can be used on all types of surfaces and is a very common paint that is used inside of the home. It is known for its fast-drying and matte finish.

Latex paint is also fast-drying and has a matte finish. However, while acrylic paint can go most places in the home and is popular to paint walls with, latex paint is most often used to paint drywall and wood, specifically.

The main difference between the two is that latex paint lacks a significant chemical base. This means that it can be easily cleaned with soap and water and releases fewer fumes than acrylic or other paints, but it also means that it is less durable and has a lower-quality finish. 

Despite these differences, because latex and acrylic paint are both water-based paints, they release significantly fewer VOCs than oil-based paints. 

Typically, the levels of VOCs will be sufficiently low if you actively ventilate a room or space for at least 24 hours after you begin painting with latex and acrylic paint.

However, if there are young children, elderly people, or immunocompromised people in your home, it is wise to ventilate even longer, for up to 72 hours. 

It is especially important to follow these recommendations if the room in question is a bedroom since sleeping in a newly-painted room involves high amounts of exposure to paint fumes.

Achieving Ventilation

There are many ways to achieve this desired length of time for ventilation:

• Turn on your range hood. Even if the kitchen isn’t the room that’s being painted, if the kitchen is near the room, then the range hood can help to remove the VOCs from the area and exhaust them out of the house.
  • If the room is on the opposite side of the home from the kitchen, then you can create a cross-draft by opening the windows in the painted room, opening all doors between the room and the kitchen, and running the range hood.
    • This will force fresh air to enter through the one open window in the room that is being painted.

• Turn on the bathroom fan. This works the same as a range hood and is also limited in effectiveness depending on the location in relation to the room being painted. You can also try the cross-draft method with the bathroom exhaust fan.

• Use a box or floor fan to move air out of the room and through an open window. Place the fan facing out of the window and turn it on. Air from the room is pulled through the back of the fan and pushed outside. If the room is windowless, you can set up a pathway of fans to the nearest window.

• Create a cross-draft. Open windows on opposite sides of the painted space or on opposite sides of the hall, room, floor, or house in order to create a draft that will carry paint fumes outside.

While not a method of ventilation, you can also utilize a space heater. This does not remove VOCs from the area, but it can speed up off-gassing.

Oil-Based Paints

The main difference between acrylic and latex paints and enamel (oil-based paints) is that acrylic and latex paints are water-based paints, and enamel is oil-based. 

Oil-based (or solvent-based) paints are known for their hard and shiny finish, while water-based paints are typically more matte. 

Oil-based paints are much more resistant to scuffs, scratches, and the elements than most water-based paints, so they are more likely to be used outdoors. For example, they are commonly used on barns. 

Enamels do, however, also have indoor applications, such as paint for wood surfaces like doors, window frames, and trim.

Despite their attractions, oil-based paints have longer drying and off-gassing times and release higher amounts of VOCs.

As such, after painting with oil-based paints, it is important to ventilate for longer than you would with water-based paints. 

You should ventilate for at least 48-72 hours after you have painted an indoor space with oil-based paints.

The longer end of this range—72 hours—is the official recommendation from organizations like the EPA and the Office of Pollution Prevention and Toxics. 

If your home has young children, elderly people, or immunocompromised people, it is wise to extend the ventilation period to 96 hours or more.

Achieving Ventilation

As you will need to ventilate longer for oil-based paints, running your range hood or bathroom fan becomes a less viable option. Running these systems is noisy and can be expensive, particularly if the painted rooms are further away from the exhaust systems.

In addition, keeping windows open across the house might not be something that you can maintain for two to three days straight.

You need to concentrate more on room-specific ventilation, and it is more worthwhile to spend a little money on setting up a temporary ventilation system.

• The box/floor fan method will still work. Just make sure that the fans are powerful and that the windows are open wide.

• Use an inline fan and a flexible duct. You can buy these quite readily and set them up with little effort. You fix the fan into the duct as per instruction, and then you run the duct out of the nearest window.
  • What’s great about this is that it provides more direct and effective ventilation that does not actively move VOCs through other areas in the home.
  • It’s also an ideal solution for a room without a window since the duct can be directed to a room that does have one.

Bathroom Paint

Bathroom paint is meant for high-moisture environments like bathrooms. 

The paint itself is formulated with a tighter structure that reduces the space between molecules and prevents moisture from penetrating the paint surface. Some even contain anti-microbial agents that slow the accumulation of mold and mildew.

Since bathroom paint’s formulation is closer to water-based paint, the average recommended time for its ventilation would be a minimum of 24 hours and up to 72 hours or more for those who are sensitive to VOCs. 

Achieving Ventilation

You can use the other methods already listed, but the obvious choice here is going to be the bathroom fan. It’s close by and leads directly to the outside.

If possible, also open a window in the bathroom to allow fresh air to more easily replace the air that is removed by the exhaust fan.

Bonus Tips

Besides the processes of ventilation, there are other things you can do to make your ventilation efficient and easy. 

• Paint in the morning. This increases the sunlight hours that the surfaces are exposed to (heat speeds up off-gassing) and also means that leaving your windows and doors open is easier and safer than leaving them all open at night.

• Choose a sunny day. Painting in the morning will be of no help if it’s an overcast day. In addition, rain can limit drying and prevent you from opening as many windows and doors.

• Don’t paint in a hurry. If the room needs to be used the following day, rather put off the painting. Your overnight guests will be better off with faded or peeling paint than in a room full of VOCs.

• Try to wait until there are fewer people in the house. The fewer people there are in the house, the fewer people there are to be exposed to the paint fumes. For example, if your child is going to an overnight camp, paint while they’re gone.

Sources

https://www.cpsc.gov/s3fs-public/painting.pdf

https://housekeepingbay.com/how-long-to-ventilate-after-painting

https://home.howstuffworks.com/home-improvement/household-safety/paint-emit-vocs.htm

https://home.howstuffworks.com/home-improvement/construction/materials/how-dangerous-are-vocs-in-paint.htm#:~:text=First%2C%20many%20VOCs%20are%20known,United%20States%20Environmental%20Protection%20Agency%5D.

https://www.uniquehomeguide.com/how-long-to-wait-to-sleep-in-room-after-painting/